Hydraulic control apparatus for internal-combustion engines and variable pitch propellers



May 19,

1953 J. s. wooDwARD 2,638,993

HYDRAULIC CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINES AND VARIABLE PITCH PROPELLERS Filed Oct. l`, 1947 3 Sheets-Sheet 1 NN Sw FMH@ Max. Vlllh May 19, 1953 J. s. wooDwARD 2,638,993

HYDRAULIC CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINES AND VARIABLE FITCH PROPELLERS Filed oct. i, 1947 3 Sheets-Sheet 2 d rw r a a a E n w E ys H www ms. om. J s mw a *um *hm um. wmm. Nmm mud cmu www mmm oww www NMNJ. www uw 3 www* Numww s. wooDwARD 2,638,993

OR INTERNAL-COMBUSTION May 19, 1953 L HYDRAULIC CONTROL APPARATUS F ENGINES -AND'VARIA'BLE FITCH PROPELLERS 3 Sheets-Sheet 5 Filed oct 1v, '1947 Aqiiar'ngy Patented May 19, 1953 HYDRAULIC CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINES AND VARIABLE PITCH PROPELLERS James S. Woodward, West Hartford, Conn., as-

signor to Niles-Bement-Pond Company, West Hartford, Conn., a corporation of New Jersey Application October 1, 1947, Serial No. 777,323

19 Claims.

The present invention relates to control apparatus for internal combustion engines, and particularly for aircraft engines driving variable pitch propellers.

The invention is illustrated as applied to a turbine-jet engine, although it may be applied to any internal combustion engine. Such engines are commonly provided with means for controlling the supply of fuel to the engine and with means for varying the propeller pitch to control the torque load on the engine.

It is an object of the present invention to provide improved means for coordinating the operations of the fuel and torque controls for an engine of the type described.

Another object of the present invention is to provide an improved engine control system including two manual control levers, wherein one control lever sets the power by setting the fuel supply and the torque load and the other lever sets the speed of the engine through the use of suitable governor mechanism.

Another object is to provide improved means for coordinating the two manual controls in response to changes in the rate of combustion air flow through the engine and the engine temperature.

A further object is to provide improved means for interlocking the two manual controls with each other and with other engine operating controls.

IOther advantages and objects of my invention will become apparent from a consideration of the appended specification, claims and drawings, in which A Figure l illustrates, somewhat diagrammatically, a turbine-jet engine suitable for use on aircraft, and certain portions of a control system adapted for use therewith,

Fig. 2 illustrates, somewhat diagrammatically, the remainder of the control system embodying my invention, of which part is shown in Fig. 1,

Fig. 3 shows a plan View, partly in section, of mechanism for interlocking the two manual control levers in the system of Fig. 2, and

Fig. 4 is an elevational view of the interlocking mechanism shown in Fig. 3, taken on the line 4-4 of Fig. 3, looking in the direction of the arrows. p

Referring to the drawings, there is shown in Fig. 1 a jet engine including a casing Ill, an air inlet I2, a multiple stage compressor I4, a compressor rotor shaft I6, a combustion chamber I8,

which is one of a number of such chambers, and` one of a corresponding number of fuel discharge nozzles 20. These nozzles are connected to a generally circular manifold 22 by means of conduits 24. There is also shown a multiple stage turbine 26, a turbine rotor shaft 23 connected to the compressor shaft IIB, and a tail pipe for discharging products of combustion from turbine 26. The shafts I6 and 28 are supported by a center bearing 32 and a rear end bearing 34, both of which are supported by the casing lll. A front end bearing is provided for the shaft I6, but is not shown in the drawing. A propeller is connected to the shaft I6 by means of a gear train generally shown at 42. This gear train may also be utilized for operating the fuel pump and other accessories.

Fuel for the engine comes from a tank (not shown) and passes through a conduit 43, a variable delivery pump 44, conduit 46, a cut-off valve mechanism 48, and a conduit leading to the fuel manifold 22.

The cut-off valve 48 includes a piston 52 adapted to block the passageway between conduits 46 and 50. The piston valve 52 is biased to open position by means of a spring 54 and is operable to closed position against the spring 54 by means of an electrical solenoid 56. Energization of solenoid 56 attracts an armature 58 connected to piston valve 52 by a stem i60. Associated with the cut-off valve mechanism 48 is a latching solenoid 62, which operates a plunger 64 biased by a spring i66 to a position adjacent the armature 58.

Energization of solenoid 56 is controlled by a push-button switch 68,rv marked with the legend Fuel Off in the drawing. Energization of solenoid =62 is controlled by a push-button switch 16, marked with the legend Fuel On in the drawing.

When switch -68 is closed, a circuit is completed which may be traced kfrom the upper terminal of a battery 12, through a conductor 14, switch 68, conductors 16 and 18, solenoid 56, and ground connections and 82 to the lower terminal of battery 12. Energization of solenoid 56 raises the armature 58, placing piston 52 in a position to block the ow of fuel to the engine. The plunger 164 is biased by spring 616 so that it then moves under armature 58, thereby retaining piston 52 in the fuel cut-off position.

When it is desired to again permit the flow of fuel to theengine, switch 10 is closed. This completes a circuit which may be traced from the upper terminal of battery 12, through conductor 84, switch 10, conductor 86, solenoid 62, and ground connections 88 and 82 to the lower terminal of battery 12. This energizes solenoid 62,

' causing plunger 64 to be withdrawn to the right so that armature 58 and valve 52 move downward under the influence of spring 54, thereby permitting the flow of fuel to the engine. The construction is such that only a momentary closure of either switch E58 or switch 10 is needed to esn tablish the desired condition of the fuel .cut-oli valve mechanism 48. ,After switch S8 has 'been momentarily closed, the fuel remains cut off until switch lil is closed. Similarly, after switch '1 0 is momentarily closed, fuel ilow is permitted until switch 63 is again operated.

The delivery of pump 44 may be yvaried 'by means of a delivery control 90, which includes a piston 92, biased downwardly by -a Spring ed. Fluid under .pressure acting on the .under -sidje .of piston S2 moves it upwardly in opposition to spring 94. The space above piston 92 is vented, as indicated at 96.

The fluid pressure acting upwardly 'on piston 92, hereinafter referred .to `as the variable control .oil pressure, may be varied in .response to a number .of ,interacting .coninol devices to '.be described ,in detail hereinater. These `vdevices ir.1 clude a manually operable fuel cam @5., a .speed responsive ,device'01 which is adj ustabfle by means of .a manu-ally operated speed cam `3.8, and a pair of .bellows 1.9.0 V.and 1,02 which together respond to an Iair pressure ldifierential in the engine.

The bellows 1.00 has its upper end nattached to a nxed :support 104, and .its 4lower end attached to an lend .plate 10.5,. ,The support 191.1 and plate 1.0.6 are connected by ,a tension spring 1538.. Air at .the pressure existing at the .discharge end of compressor .I4 is conveyed to the .interior .of bellows 100 through a conduit .11.0.

The :bellows 1.02 has its lower v.end'mounted on a nxed support .1.12, and its upper .end .closed .by a xed plate 1.14. Airat .thestatc pressure existing at the inlet to the compressor 1.4 'is conveyed to the interior of bellows 102 by means of a .conduit .1.115. The plates .1.0.6 .and `1.141 .are connected by `a rigid rod .11.8.

A lever 12.3 is pivoted near its center on the rod 11E. The `left end .of lever i213 is connected by .means of a pin-andslot connection .to a valve Stem 122. Thestcm 122 extends into .and oper- `ates .a piston valve mechanism r1241, ,of conventional construction, whch controls the ilow .of hydraulic .uuid 'to the .opposite .ends of .a piston type hydraulic servomotor 125.

Hydraulic .fluid for operating the servomotor 12S .comes from a-sui-t-able reservoir (not shown) and flows through a pum-p 1.2.8, which may `be engine driven, and whiohis provided with a discharge pressure regulating relief .valve 13B. From .the pump 121.8, the Iluid, which may be a suitable oil, flows through a .conduit v132 to the valve 121i. .Fluid may pass .from the valve 124 tothe `oil reservoir .through drain connections 134 and 13B.

The servomotor '126 operates ,a rod 1.38, which is connected through pin-and-slo't connections to the right .end or lever 12b, and to .bell-crank levers .40 ,and 14.2..

Upon .an increase vin the differential between the .compressor dischargepressure and the compressor inlet pressure, bellows 180 .is expanded, thereby moving .rod I I3 downwardly. Lever 120 pivots .about its .right end, thereby moving stem 1.22 downward and `operating vthe valve mechanism 125 to supply fluid at high pressure to the upper .end o f servomotor 12B and to .connect the lower .endof .seryornotor 125 to thev drain conduit 134. This causes the .servomotor to move rod 138 downward, thereby `pivoting llever Y.12.0 about its center, and raising the valve stem 122. This operation continues until the valve 124 is restored to its original position, wherein no luid is supplied to servomotor 126.

It may therefore be seen .that the valve 124 and .servomotor .126 operate .to Supply .a POWGT boost for .the bellows and L02, so that the Work done through rod 38 as a result of their deiiection need not be supplied by the bellows themselves, but is supplied by the oil pressure.

Tlhe bell-fcrank lever is pvotally mounted on lfixed support i144, and its lower end is pivotafllyconnected to Aa link 146 which carries at its @n.dacircularbearing 148. The bearing 1138 slidably contacts .on its opposite surfaces a pair of --evers .156 and 1.152. The right end of lever 150 is pvoted on a nxed support 154. The left end of 'lever 151i is biased downwardly by a spring 156 retained. between the end of lever 150 and the iixed support 1M.

The left end of lever 152 is .pivotally attached to a .ixed support 1'5'1. Itsright `end is .connected through a pin-andslot 'connection to a piston rod 153. Rod 158 is lconnected to apiston 1611 in a motordevice 41&2. The .chamber above piston Idil `in .the motor .device `1.52 is vented to atmosphare .at 161i. The pressure .space below piston it@ .in .the motor device 152 ,is supplied with fluid under pressure through .conduit 1.66,.

The position .of piston Il is .dctermned'by the balance between the pressure under it acting upward and the force of .spring 156, which acts downwardly `.on .piston 1.6.0 through 'the lever 150, bearing c1.118, .lever 1.62, and rod 158. It maybe seen that the lateral position .of y.bearing 148 `determines .the mechanical advantage 'between spring .1.5 S .and the .pistonlli'm The pressure below the piston 1,60 is con trolled by .a valve mechanism .108., `of ,generally conventional construction. The valve .mechanism .1.68 includes a piston valve having two lands which, in the position .Shown .in .the drawing, lie on theopposite sides .of a central .port leading through conduits 1.7.23 and 1.66 to the chamber below the piston i60.. The `-conduit 15,6 also connected through a .conduit `v1.12 to the .chamber below the piston B2 in the fuel pump delivery control. When .the piston valve i163 is .moved downward from the neutral position illustrated .in the drawing.,..it .admits high pressure fluid from the pump 128 through conduits 1'14, 11B past valve [1.6.8 .into .conduits .1 10 and 1.6.6, thereby increasing the 'pressure under the pistons 9.2 .and 160. 'When the .valve is moved .upwardly ,from its neutral position, it connects the Spaces under pistons $2 and 16.0 to a `drain .conduit 1.7.3, .thereby decreasing the pressure under the pistons S2 and 161i.

The valve 1.08 is operated by a stem 1.80, whose upper end is pivoted to a lever 1182.. The left end of lever lZ .is connected through apin-and-slot connection to the piston rod 1.58. The right end of lever '1.02 .is spacedslightly above, but may be operated by the Afuel cam 9'5. A spring 131i vis retained between lever 32 and xed support l18S, and biases the lever 182 downwardly toward the cam .95. The right extremity of 'lever 182 is engaged by a lug 187 on a rod 188 operated by a piston in a speed responsive motor device 192.

'It may be seen that when the valve 168 is Ymoved downwardly from the position shown, fluidV under high pressure lis admitted lfrom conduit 1'16 into conduit 110 and thence through conduit 1&5 to the chamber under piston 181i, ythereby raising piston 15B .and rod 150, which movement is transmitted 'through lever 82 back to .stem |80 and valve |68 to restore it to its neutral position. Similarly, upward movement of valve |68 results in a downward movement of piston |69.

The speed responsive device 91 includes a pair of flyballs |92. The flyballs are mounted on a head |94 driven by the engine through suitable gearing. The inner ends of the L-shaped iiyballs act on a vertically movable rod |96 which is attached at its upper end to a sleeve |98 slidable within a stationary cylinder 290. end of rod |96 extends through the head |94 and is engaged by one end of a tension spring 292. The other end of spring 292 engages a lever 294 which is pivotally mounted at its left end on a xed support 296. The speed cam 98 engages an intermediate point of lever 294.

A piston valve 298 moves within the sleeve |98, and is connected to a stem 2|9 which extends upwardly to a point of pivotal attachment with a lever 2|2. A pin-an-slot connection is used between stem 2|9 and lever 2|2. The right end of lever 2|2 is pivotally attached to a fixed support 2|4, and its left end is engaged by a lug 2 |6 attached to the rod |88. A spring 2|| biases stem 2|9 downwardly.

The tension of spring 292 may be set by manipulation of cam 98, and determines the speed of the engine at which the sleeve I 98 is held by the flyballs in the neutral position wherein the port leading to conduit 2 I8 is blocked. If the engine speed increases above the value determined by the cam setting, then the flyballs |92 move the rod 96 upwardly against the spring 292, thereby moving the sleeve |98 upwardly and admitting fluid at high presure from conduit |14 to a conduit 2|8 leading to the space under the piston |99. This increases the pressure under piston |99, moving the rod |88 upwardly. This motion is transmitted through lug 2|6 and lever 2|2 to the valve stem 2|9, causing the latter to move upwardly until the valve 298 again blocks the ports leading to conduit 2|8.

Similarly, if the speed falls below the previously selected value, then the conduit 2|8 is vented to low pressure through the space below the piston valve 298, the space below the sleeve |98, and the drain connection 229. The valve mechanism |98, valve 298 and the motor device |92 together operate to increase the power available to move the piston rod |88 and its associated mechanism. By the use of the valve and motor device, the power moving the rod |88 is taken from the engine driven pump, rather than from the flyball governor device 91.

When fluid under high pressure is admitted to conduit 2|8, the piston |99 is raised and lug |81 raises the end of lever |82 and thereby valve |68 to reduce the now of fuel to the engine. If the engine speed drops below the value selected by the tension of spring 292, then. the port leading to conduit 2 |8 is connected to the drain, and piston |99 is lowered. Downward movement of piston |99 causes rod |88 and lug |81 to move downward, and the lever |82 follows this Adownward movement until its motion is limited by the cam 95. This downward movement of lever |82 moves the valve stem |89 in a fuel flow increasing direction. The cam 95 therefore limits the fuel available to increase the engine speed to its selected value. The cam 95 may therefore be said to limit the rate of acceleration of the engine.

Means are provided to limit the fuel ow whenever the engine exhaust temperature exceeds a predetermined value. This means includes a thermostatic valve controlled by the engine ex- The lower 6. haust temperature and indicated diagrammatically at 222. vThe valve 222 controls a motor device 224. The device 224 includes a piston 226 biased downwardly by means of a spring 228. The space under the piston 26 is connected through a valve 22 and a conduit 239 to the fluidsupply conduit |14 whenever the valve 222 is open.` A restricted drain conduit 232 is provided for this space. Whenever valve 222 is open, pressre builds up under the piston 226 because of the restriction 232. If the temperature approaches an unsafe value, the valve 222 opens, increasing the pressure under piston 226 and raising the rod 234 until its upper end engages the leverV |82 and moves it upwardly in a fuel ow decreasing direction. v

Torque control The main portion of the torque control is shown in Fig. 2, but certain parts of the torque control of Fig. 2 are repeated in Fig. 1 to show their relationship-to the other elements of Fig. 1. f The torque control apparatus utilizes a torque meter, generally indicated at 259 in Fig. 2, which.

may be of any suitable type. For example, a torque meter such as that shown incidentally in the copending application of Leighton Lee II, Se-

rial No. 654,979, led March 16, 1946, may be used.v

This type of torque meter provides a fluid pressure which varies in accordance with the output' torque of the engine. This fluid pressure is communicated through a conduit 252 to a chamber 254 under a piston 256 in a control valve mechanism generally indicated at 258. Piston 256 acts upwardly on the stem 269 of a conventional piston valve 262. The control valve mechanism 258 connects the propeller pitch control mechanism selectively to a source of fluid at high pressure, represented herein by the conduits |32 and 2'64, or to a drain conduit 268.

The control valve mechanism 258 is connected byk a conduit 266 and a reversing valve 219 with one or the other of conduits 212 and 214 leading to the opposite ends of the cylinder of a hydraulic servomotor 216. The servomotor 216 includes a piston 219 biased to a central Position by means of opposed springs 289 and 282. The piston 218 is connected by a rod 284 to a propeller blade angle control of conventional'type. The central position to which piston 218 is biased corresponds to the fiat or zero pitch angle of the propeller blades.

When the reversing valve 219 is in the position shown in the drawing, the conduit 212 is connected to the conduit 266. Hence the control valve mechanism 258 regulates the pressure above piston 218, which is moved downwardly from its central position, deflecting spring 282 in proportion to the magnitudeof the applied pressure. Conduit 214 is at this time connected through transfer valve A219 to a drain conduit 288. Movement of piston 218 in the lower part of its range of travel causes operation of the propeller blade in its forward thrust range.

Movement of piston 218 above its central position operates the propeller blades in their reverse thrust range. Such operation is accomplished by means of the transfer valve 219. This valve is operated by means of a solenoid 298 which, when energized, attracts an armature 292 connected to valve 219. The armature 292 is biased upwardly by means of a spring 294.

When ythe solenoid 299 is energized, armature 292 is drawn downward, connecting conduit 214 to the conduit 266, and connecting conduit 212` 7 to a drain conduit 266.v The piston 218 of servoF motor 216 is then moved in the upper half of its range of travel, its position depending upon the pressure supplied to its underside through conduits 263 and 214.

The positions of the fuel cam 95 and the torque. cam 282 are determined by the angular position ci a manual control lever 36u. The cams 95 and 262l may be on either the same shaft as lever 3h0 or on a `shaft which moves concurrently with lever 390. This shaft also turns a com 302 which operates a switch 364 and a cam 306 which operates a switch 3&8.

The speed cam 'S8 is operated by a manual control lever 13H?, which also turns a cam 31.2 operating a switch 3 l 4.

The center lines A, B, C, D and E on cam 98 indicate the portions of the cam which engage its associated follower when the control lever 3H] is moved to an angular position indicated by the correspondingly lettered center line adjacent it. Similarly, the Vcenter lines F, G, I-I, I and J on cams 95 and 282 indicate the cam portions which are engaged by the respective followers at the several positions of control lever 300.

When control lever 306 is in position G, the fuel flow is set by cam 65 at a minimum value, suitable for idling. At this position of control lever 360',- cam 326 closes switch 308 so that the featherlng control may be operated, The cam 306 opens switch 308 at all other positions of the manual lever 300, so that the feathering control may not then be operate-d. The object of this interlock is to prevent feathering of the propeller at a time when an appreciable amount of fuel is being supplied to the engine. Feathering the propeller greatly increases the torque load on the` engine shaft and usually results in stalling the engine. If an appreciable quantity of fuel is being delivered and burned in the engine at that time, the engine will overheat'and may even burn up.

When the manual lever sill) is moved to the range of' positions between position G and position F, the cam 3D2 operates switch 304 to energize the reversing solenoid 296. The energizing circuit for solenoid 260 may be traced from the upper terminal of a battery SIG through a conductor 313, switch 304, a conductor 320, a conductor 322, solenoid 29D and ground connections 324 and 326 to the lower terminal of battery 3l6. The fuel flow and propeller torque are then determined by the cams 95 and 232, respectively, but the propeller torque is in the reverse direction, so that the propeller is then used for braking purposes.

The cam 312 and switch 3 l 4 interlock the speed control lever 3m with the feathering control so that the latter may not be operated unless the speed control lever is in a minimum speed position. Otherwise, the slowing of the engine by the feathering of the propeller would cause the speed control to respond by calling for an increased fuel flow, which might cause burning up of the engine. Closure of switch ,3M also energizes the fuel-on control of Fig. 1 to cut ofi the fuel supply when lever 316 is moved to position A.

This energizing circuit for the fuel-oil control may be traced from the upper terminal of battery 336 through switch 3l4, a conductor 369, conductor 16 (see Fig. l), solenoid 56, and ground connections 80 and 346 to the lower terminal of battery 336.

When it is desired to feather the propeller, a push-button switch 32B is depressed. This com.- pletes an energizing circuit, for a motor 332 driv:

ins a hydraulic iluid pump 334. The energizing circuit for solenoid 330 may be traced from the upper terminal of battery l336 through switches 6M, 368, a conductor 33B, switch 328, conductors 346 and 342, solenoid 330, and ground connections 3M and 34.6 to the lower terminal of battery 336. Energlzation of solenoid 330 moves an armature 348 downwardly against the action of a biasing Spring .356. Movement of armature 348 operates a feathering valve 352 downwardly, admitting hydraulic fluid at bien pressure from Supply conduit |32 through check valve 35e in conduit 356 directly to conduit 266 and thence to the upper end of servomotor 216, where it drives piston 218 downwardly in the'teathering direction.

The energizing .circuit for motor 332 may be traced from the upper terminal of battery 336 through Switches 3M and 308, conductor 338, switch 326, conductors 358 and 360, motor 332, conductor 362, switch 364, and ground connections 366 and 34.6 to the lower terminal of batterr 336.

The switch 364 is operated by means of a pres-` sure responsive device generally indicated at 358 which responds to the pressure in supply line I32, and maintains the switch 364 open unless the pressure in the supply line drops below value determined by the strength of a spring 316 in the mechanism 366. As long as the engine is running, fluid under pressure is available at the supply line 132, and itis not necessary to operate the motor driven pump 334 unless the pressure in the supply line 32 fails. The switch 364 keeps the motor from running as long as pressure is maintained in supply line 32. When pump 334 operates, it delivers fluid through a conduit 312 and a check valve 314 to the conduit 356 and thence to the servomotor 216.

When it is desired te unfeather the propeller, a pushvbutton switch -36 is operated. This complates energizing circuits for the motor 332, the feat/heling solenoid 330, and the reversing solenoid 23D. The circuit for motor 332 may be traced from the upper terminal of battery 336 through a conductor 318, switch 316, conductors 336 andill, motor 332, conductor 36,2, switch 364, and sTound connections 366 and 346 to the lower terminal of battery 336.

The energizing circuit for ieathering solenoid 336 may be traced from the upper terminal of battery 336 through conductor Slt, switch 316, conductors 382 and 34,2, solenoid 330, and ground connections 344. and 346 to the lower terminal of battery 336.

The energizing circuit for reversing solenoid 290 may be traced from the upper terminal of batter-y 336 through conductor 318, switch 316, conductors 384 and 322, solenoid 2905, and ground connections 324 and 346 to the lower terminal of battery 336.

This operation is similar to the ieatnering operation except that the propeller is run in the opposite direction because of the action of the reversing valve 290.

The interlocking between the manual levers 3m) and .31s is illustrated in Figs. 3 and 4. Each of the levers operates adjacent a stationary frame member which is provided with a series of notches. These notches have been lettered with reference characters corresponding to those of the center lines indicating the various lever positions in Fig. 2`- An interlocking bar 4st lies between the two levers, which are slidable along the shaft 4,02 von which they are pivoted. It will be readily understood that both levers do not more with the shaft 402 but that the motion of one of them is transmitted to its associated control devices by other means. v L

The speed control lever 3H) is in the cruising range between positions D and E. Position D is the operational idle position, and all the positions left to the position D correspond to lower speeds which are used during star-ting, ground idle, etc. When the speed lever is moved to the extreme left hand position, indicated at A, the fuel is cut off from the turbine by the operation yof switch 314, as previously. explained.`

It should be noted that the construction of the interlocking bar and the depths ofthe several notches are such that the speed control lever 3 iii cannot be moved to the left past position D unlessY the power control lever 300 is at position G, cor,- responding to minimum fuel iiow and torque. Likewise, the power lever 300 cannot be moved out of its minimum torque position unless lthe speed lever 3l@ is at least up to the operational idle position. y

It should also be noted that the interlocking bar 4&0 prevents .the power control lever 300 from being moved to the right beyond position I unless the. speed lever is in its maximum speed posi-,- tion E.

When the engine is shut down, the power lever 30d is at position G and the speed lever 3l@ is at positionA, so that fuel is cut offfrom the engine. When starting, the engine is rst cranked to firing speed, thefuel valve is opened and the speed control lever is advanced to position B, thereby adjusting the fuel rate for proper acceleration of the turbine. The next position C of .the speed control lever 310 increases the speed' to give the proper air flow to maintain the turbine temperature while idling on the ground. When the speed lever 3H! is advanced to position D, the turbine speed is brought up to the lower limit of the range used for normal flying, operation, and advancing the speed lever further to E gives top engine speeds for maximum power output.

Whenthe speed lever 3|() is in the range from D to E, the power lever 300 can be moved from its minimum torque position G. As the power lever is moved to the right toward positions I-I, I, and J, the torque cam is rotated to provide increasing propeller torque. At the same time, the fuel cam increases the fuel iiow t support this torque. f

Although three separate batteries are shown in the drawings, these are shown only to simplify the wiring diagrams. In any practical construction, a single suitable source of electrical energy would be used.

The `terms and expressions which I have employed are used as terms of description. and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim as my invention:

l. Control apparatus for an internal combustion engine having a fuel supply means, and a variable pitch propeller driven by said engine; comprising: propeller pitch varying means, a fuel supply cut-off mechanism, manual control means movable to a position wherein said control means is effective to operate said mechanism to cut off the iiow of fuel to said engine, means for operating said pitch varying means in a direction to feather said propeller, and means for preventing operati-on of said feathering means unless said manual control-means is in said position.

2. Control apparatus for an internal combustion engine and a variable pitch propeller driven thereby, comprising: propeller pitch changing means, means for regulating the fuel supply to said engine, a iirst manually movable control de. vice, means including said device for controlling both said pitch changing means and said fuel supply regulating means, speed responsive means for additionally controlling the fuel supply, and a second manually movab-le control device for varying the response characteristic of said speed responsive means; said control devices being operatively interconnected sothat the movement of one device is limited by the position of the other device.

Control apparatus as in claim 2, including propeller torque measuring means, and in which said means for controlling said pitch changing means includes said .torque measuring means and operates said pitch changing means to produce a value of propeller torque determined by the position of said first manually movable control device.

4. Control apparatus as in claim 3, in which said speed responsivevmeans operates to reduce the fuel supply when the speed exceeds a value determined by said second control device, and including interlocking means to preventthe setting of said first control device at a position corresponding to a torque greater than a predetermined minimum value unless said second control Ydevice is at a position corresponding to a speed greater thana predetermined value.

5. Control apparatus for an internal combustion engine having a fuel supply means, anda variable pitch propeller driven by said engine; comprising: propeller pitch changing means, propeller torque measuring means, a first manually movable control device, means including said torque measuring means and said control device' 6. Control apparatus as in claim 2, including means for reversing said pitch, and means responsive to a movement of said rst control device to a predetermined range of positions for operating said pitch reversing means.

7. Control apparatus as in claim 6, comprising means including said pitch reversing means for feathering and unfeathering said propeller, said unfeatheringV means being operable independently of said first control device.

8. Control apparatus for an internal combus.

tion engine having an air supply and a fuel supply means, and a variable pitch propeller driven by said engine; comprising: propeller pitch changing means, propeller torque measuring means; means, responsive to the pressure, but independent of the volume, of the air supply to said engine, for regulating said fuel supply means, a. first manually movable control device, means including said' torque measuring means and said control device for controlling said pito-li changing means toproduoe evalua of propeller torque determined by the position of' said. control device, a second manually movablev control e-I vice for controlling said. fuel supply regulating means, and speed responsive means, operatively associated with said fuel supply means, for reducing the fuel. supply to said engine when the speed exceeds a value determined by the position of said second control device..

9. Control apparatus as in claim 9 including means for feathering and unieathering said: pro pellerr said unfeathering means being manually operable independently of the position od said. second control device.

10. Control apparatus as in claim 9, in which;k said means for controlling; saidv pitch; changing means includes lpitclsi reversing means andmeans responsive to a. movement of. said iirst control device to; a predetermined range ci positions for operating said pitch reversing means, and said unfeatbering means also includes said pitch ree versing. means.

11. Control apparatus as in claim 8, including means responsive. to the. mevementof Said Second control device to a zero. speedA position; for cutting on the now ci fuel to said engme.

l2. Control apparatus asin claim l1, including manually operable means independent of` said rst control device. for featherng Saldi pro-seller., and means for preventing operation oiV said. feathering means unless Said `second control de,- viceis in said zero speed position..

13. Control. apparatus for an. internal combos-- tion` engine; having an air supply andy ay fuel supply means, and aV variable pitchpfopeller driven by said engine, comprising; propeller; pitch. changingY means, means, responsive tothey pres-A sure, but independent. of the;V volume.. of. the air' supply to said engine, for regulating said! incl supply moana a. maially movable; control device, means including denise: for control. ling both. said pitch.. changing means and. said fuel. supply regulating Ineens...` sneed responsive; means for additionally controlling the-fuel supply', and a. second manually movable. control der vice for varying the, response characteristic oi said speed responsive means :g said. means forcontrolling. said pitclr changing means including prof-- peller torque measuring. means and. said-.pitch changing tol proxima ai value of: propeller torque determined. by the. position4 oi. said iirst control device.

14. Control apparatus as claim r3; inv which, said speed responsive means operates to nochma the fuel supplywhen the speed exceeds; a value determined by' said second control dev-ice, including interlocking means to prevent. the set-a ting of said rst. control device atI a. position4 core responding to a. torque greater atpredetea mined minimum. value unless. said second: control. device is. ata position. corresponding to a. speed greater' than a predetermined.. vallan.

15. Controli apparatus for anv internal combina tion engine and a. variable ptclr propeller driven. thereby, comprising.; propeller pitch; changing means, means forY regulating the fuel. supply to said engine, a rst manually movable control device, means including said device for control-.- ling both said pitch changing means and said fuel supply regulating means, speed responsive means for additionally controlling the fuel supl-r ply, a second manuaily movable control device for' varying the. response characteristic o1" said speed responsive means; means for reversing the pitch of. said propeller, and means responsive to a, movement of said first control. device to a predetermined range of positions for operating said pitch reversing means'.

16. Control apparatus as in claim 15, compris.- ing means including said pitch reversing means for feathering and unfeatherng said propeller', said unieathering meansl being operable. indet-v pendently of said first control. device.

17. Control. apparatus for' a variable pitch propeller, including. propeller pitch varying and reversing means, propeller torque measuring means, a manually movable control device, means including said torque measuring means and said control device. for operating said pitch varying means to produce a value of propeller torque determined by the position of said control device, and means, responsive to a movement of said control device. toy a. predetermined range of. positions and operatively associated with such pitchl reversing means',r for reversing the pitch. of said propeller; said. pitch varying means. includingl a hydraulic motor comprising a. piston movable in'- a cylinder and' operatively connectedto saidpro peller, and a. pai-r of springs acting oppositely on said piston. and biasing it to.l a. central. posi.- tion corresponding to zero pitch oi said propeller; and said operating means including; meansv for applying a fluidund'er a variable pressure to one side of said piston to oppose one of said springs and thereby position said piston ori one: side of said. central positions 18. Control apparatus asf in. claim 1.7, in. which. sa'ix reversing rmeans includes a reversing valve for directing the application of said fluid to the oppositeA side ofV said piston to oppose: the other of said springs and thereby positionv said piston on the other side of said central position..

1.9L Control apparatusas. in claim 17, comprising means including said reversing valve for featheringv and unieathering said propeller, said unieathering means being manually operable; independently of the position of said control de.- vice..

JAMES El.v WOQDWARD.

Beierences Cited in the4 iile of this. patent UNITED STATES PATENTS NumberA Name Datev 2,207,042' llifaseigeA July 9, 1940A 2,217,364' Halford et al Oct. 8, 1940L 2;,303g998 Holley Dec. 1, i942 2,308,228' Mattencci Jan. l2, i943 21322,',303 Martin June' 22, 1943 2343,378 Kieser" Mar; 7", 1944 2,391,629 Keller Dec. 25, 19'45 2,402,065 Martin June lli, 1946 2,412,360 Schorn Dec. l0, 1946 2,428,531 Schorn Oct. "l, 1947 

